How US jogger Mollie Tibbetts' disappearance unfolded

The disappearance of Mollie Tibbetts from a small town in Iowa has become one of America’s most talked-about missing persons cases.

The 20-year-old was last seen during an evening jog on July 18 in Brooklyn, Iowa. She was reported missing the following day when she failed to show up to work.

At the time, the University of Iowa student was staying at the home of her boyfriend, Dalton Jack, to take care of his dogs while he was away for work.

Jack has been ruled out as a suspect because he was working at a construction site 160 kilometres away at the time of her disappearance.

Mollie Tibbetts (AAP)

The last correspondence Jack said he had with his girlfriend of three years was a Snapchat photo he’d opened around 10pm the day she went missing. The photo was a selfie of Tibbetts that appeared to have been taken inside.

According to Kevin Winker, director of investigative operations at the Iowa Department of Public Safety, there are now between 30 to 40 investigators working on the case of Tibbetts’ disappearance each day.

A week after her disappearance, authorities began investigating a pig farm 15 minutes from where Tibbetts was last seen, after a red shirt similar to her daycare centre uniform was found nearby.

Pig farmer Wayne Cheney, 56, has spoken to investigators twice and told Fox News the FBI has searched his home, some of his property, and his mobile phone. He has also refused to take a polygraph, despite a request by law enforcement.

Local police then responded to a reported sighting of Tibbetts at a truck stop in Missouri on July 26, eight days after her disappearance.

“Officers conducted a thorough search of the area, spoke with all possible witnesses, and reviewed all available video footage,” a police statement said.

Then, last Sunday, the body of a woman in her twenties was found about an hour from where Tibbetts was last seen, but officials confirmed later in the afternoon that it was not her body.

Kevin Winker of the Iowa Division of Criminal Investigation speaks about the disappearance of 20-year-old Iowa college student Mollie Tibbetts during a news conference Tuesday, July 31, 2018. (AAP)

Tibbetts’ family has since set up a crowdfund to finance a reward for her return, raising more than AUD $230,000 in one day.

The “Bring Mollie Tibbetts Home Safe Reward Fund” now sits at over AUD $400,000.

“We believe that Mollie is still alive,” mother Laura Calderwood told a media conference. “If someone has abducted her, we are pleading with you to please release her.”

In footage released on Wednesday, Tibbetts is seen laughing and behaving normally in the days before her disappearance. The iPhone and Fitbit she's pictured holding in the video are being viewed as important factors in the investigation into her whereabouts.

Mollie Tibbetts’ disappearance: a timeline

July 18th

Tibbetts is last seen going for an evening jog in running shoes, shorts and a black sports bra. She is staying at her boyfriend’s home at the time.

Boyfriend Dalton Jack receives a Snapchat photo around 10pm - a selfie of Tibbetts, which appears to have been taken indoors.

July 19th

Tibbetts’ brother, Jake, sends her a text message in the morning asking if she wants to borrow his car. She does not respond.

“I didn’t think much about it at the time, but now I think about it a lot,” Jake told Fox News. “About how weird it was not for her to text back.”

After failing to show up to work, Tibbetts’ parents reported her disappearance. Dalton Jack returns from work trip early after being informed Tibbetts is missing.

July 25th

Pig farmer Wayne Cheney has his property, home and mobile phone searched by authorities, reportedly after a red shirt, similar to Tibbetts’ daycare centre uniform, is found near his home.

(Facebook)

July 26th

A potential sighting of Tibbetts at a truck stop in Missouri is investigated by local police, prompted by a Facebook post of someone who believes they saw a woman matching Tibbett’s appearance.

August 3rd

Kevin Winker says authorities are “not in a position to say who is a suspect, who isn’t a suspect or that there are suspects” when questioned about Cheney during a news conference.

August 5th

The body of a white female in her twenties is found in Lee County, about an hour from where Tibbetts was last seen. Officials confirm the body does not belong to her.

August 6th

Investigators speak to Cheney for a second time. He continues to deny any involvement and refuses to take a polygraph despite a request by law enforcement.

August 8th

A video of Tibbetts filmed the day before her disappearance is released.

Filmed by friend and co-worker Olivia Ritter, Tibbetts is seen sitting on the floor of the art gallery at Grinnell College.

“She was totally normal that day,” Ritter tells Fox News. “All of her actions were the same as they had been previous days.”

August 9th

Iowa man Devin Riley tells Good Morning America he believes he was the last to see Tibbetts before she went missing.

Riley says he saw her jogging past his house, as she did three or four times a week, with her hair in a ponytail.

"She was wearing like a neon pink sports bra with black khaki yoga pants and an armband with her music device, or phone...hair in a ponytail, just jogging like normal, any other day," he told the US news program.

He says he thought nothing of it until he "heard somebody was missing and it really hit me that I haven't seen that runner since then."